The best advise I would give anyone who is considering living in the boat world is to start off small. Nearly everything you learn from a smaller vessel is transferable to a larger vessel. Learn your safety
features, learn your emergency
procedures. figure out what you would do if you had a fire aboard, or leaking. If you think it all through when there isn't an emergency- when there is one your responses will be automatic- no panic. Never panic!
Study your rules of the road and pick the brain of the more experienced captains you meet along the way. If you can swing it find a local captain
who will give you a few lesson aboard YOUR boat. Get to know what you're are supposed to do when interacting with other vessels as well as what they are supposed to do (and find out what the knuckleheads do so you can avoid entanglements). I keep my boat in the water
year round because I don't mind cold weather
(my grand dad used to say there is no such thing as bad weather
, just inappropriate clothing) and there are so many fewer idiots out there off season.
Study everything, learn how to fix anything; even if it is just enough to get you to shore. Learn the areas you are going to navigate; become a local expert. Take the boat out frequently, even in less that perfect weather and conditions so you can learn how the boat handles in those conditions close to home so when (not if) you face them away from home you know what to do without fear. When you have people aboard with you always be confidant in your abilities and those of your craft- it is better to be wrong than indecisive; you can almost always fix a mistake later but you can not fix wishy washy.